Among the Mehinaku Indians of Brazil, as among many similar tribal peoples, men and women are separated and opposed by fear of sexual pollution, rituals of sexual antagonism, and an exclusive male organization. A wide variety of historical, ecological, structural and psychological theories explain the pattern, but in many cases the data supporting these theories are weak. The psychological explanations, for example, see the ambivalent relationship between the sexes as an expression of the Oedipus complex and incomplete identification with the male role. The evidence in support of this position, however, is drawn largely from the psychological analysis of institutions rather than individuals. The proposed summer field work, part of an extended ethnographic study of the Mehinaku Indians, seeks to document the nature of men's and women's roles from the perspective of both social and psychological anthropology.